it really depends on where the comma is
you could think of it as a 'Radar-Control' Service
That is a Service provided by a Radar Controller
As opposed to a Radar 'Control-Service' where some guy with a Radar tells you what to do. (as they might in 'C' and above)
It is not in the spirit of the intent of class D airspace that everyone should be directed (commanded or controlled) as in "you are cleared to x, route this way, hold 1 mile north of the threshold, report when you have y in sight, behind the Kyrgyzstani Cessna 152 at 5 miles cross the date line etc.
It is not the responsibility of ATC to seperate VFR traffic from IFR, and having now routinely done so for so long they have created the danger that pilots will believe this will happen as a matter of course. This and the unfortunate emphasis on the word 'control' leads to confusion.
It is understandable that controllers do this, since they live in terror, and have little faith in pilots.
Yes once a clearance is given and accepted, the VFR pilot must comply with it untill she says that she no longer wishes to.
I often hear PPilots being bullied, sometimes the pilots need to remind ATC that its their ass in the air. Most ATC is superb at this, particularly at bigger airports.
I note a slight difference between 'controllers' Inverted81 and Good Egg, with G'egg slightly more in the I'm going to tell you what to do camp?